Extended surface exchange having a tubular portion

ABSTRACT

In preferred form, a heat exchanger including an elongated tubular member, with a wire fin formed along the length thereof. The fin has a plurality of axially spaced portions bent around an arcuate segment of the outer periphery of the tube for conductive heat transfer between the fin and tube. Other portions of the wire fin are looped radially outwardly of each of the bent portions to form a flow passageway between the fin and tube for convective heat transfer.

United States Patent Byron L. Brucken Dayton, Ohio [21] AppLNo. 868,401 [22] Filed [72] Inventor References Cited UNITED STATES PATENTS 1969 822,372 6/1906 Kltchen........................ Division of Ser. No. 501,991, Oct. 22. 1965, FORElGN PATENTS Pat. N9. 3,482,298. 425,376 3/l955 Great Britain................ July Primary Examiner-Frederick L. Matteson Assistant Examiner-Theophil W. Streule [45] Patented General Motors Corporation Detroit, Mich.

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INVENTOR. Byron L. Bracken BY His Attorney PATENTEDJUL13|97| 3.592262 SHEET 2 0F 2 INVENTOR. Byron L. Bracken BY 5M His Attorney EXTENDED SURFACE EXCHANGE HAVING A TUBULAR PORTION I This is a Division of Ser. No. 501,991 filed Oct. 22, 1965 now U.S. Pat. No. 3,482,298 granted Dec. 9, 1969.

This invention is directed to a wire fin and tube heat exchanger and more particularly to a wire fin and tube heat exchanger having an extended wire fin surface.

Heat exchangers of the type having an extended heat transfer area, such as are commonly used as evaporators in refrigerators, air conditioners and the like, are often characterized by the provision of a large number of separate parts that make up the heat exchanger unit. For example, in many cases, a plurality of fins are separately mounted-with respect to the tubing of the heat exchanger to produce an extended heat transfer surface capable of performing a given heat transfer function within a limited volume of heat exchanger unit. Another way of increasing the heat transfer surface in a heat exchanger is by the provision of a wire fin surface thereon. Wire fin type heat exchangers have taken many forms, but to a greater or lesser degree have all required rather complex methods of manufacture to produce the resultant article.

An object of the present invention is to improve heat exchangers by the provision of a combination tube and wire arrangement that includes a continuously wound wire fin on a predetermined length of a fluid conducting tubular member wherein the continuously wound wire fin is formed as a continuously angularly offset plurality of loops along the length of the tubular member with each of the loops having a portion thereof bent angularly around the tubular member in good heat transfer contact therewith and another portion thereof located in radially spaced relationship with the tubular member for defining an extended heat transfer surface on the tubular member.

Still another object of the present invention is to improve extended surface heat exchangers of the wire fin type by the provision of a continuously formed wire fin located along the length of a tubular fluid flow member and wherein the continuous wire fin is formed as a plurality of interconnected, angularly offset loops around the outer circumference of the tubular member with each of the loops being located at spaced apart points along the length of the tubular. member and including an apex portion thereof located radially outwardly of the circumference of the tube and a radially inwardly bent portion thereof wrapped around the tubular member in good heat transfer contact with an arcuate portion of its outer circumference.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodi ments of the present invention are clearly shown.

IN THE DRAWINGS:

FIG. 1 is an enlarged view in front elevation of the present invention showing the tube and wire at one stage of manufacture thereof;

FIG. 2 is a view like FIG. 1 showing a subsequent stage of manufacture;

FIG. 3 is a view like FIG. 1 showing a still further step in the manufacture ofthe invention;

FIG. 4 is a view like FIG. 1 showing a step of the manufacture advanced from that shown in FIG. 3;

FIG. 5 is a view like FIG. 1 showing a step advanced from that shown in FIG. 4;

FIG. 6 is a view like FIG. 1 showing a step advanced from that shown in FIG. 5;

FIG. 7 is a view in end elevation of the assembled tube and wire heat exchanger of the present invention showing a portion ofthe formed loops thereon; and

FIG. 8 is a vertical, sectional view taken along the line 8-8 of FIG. 7;

In FIGS. 1 through 6, various stages of a wound tube and wire exchanger are specifically set forth, including the initial about the outer circumference of the connection of the wire to the tube, as shown in FIG. 1, at which point the wire and tube are at their initial starting point with the wire 40 being wrapped about the outer periphery of the tube 48 with the flat surface 46 ofthe wire 40 being in contact with the outer circumference of the tube 48 from the point to a point tangent to the tube thence to pass about the point 102.

As shown in FIG. 2, the point 102 has a reach of wire 122 between it and point 104. The tube, is advanced 34.

In FIG. 3, a further stage of the winding is illustrated rotated 360 from its initial portion and the tube rotated 360 plus 60.

At this time the reach of wire 122 about the points 102, 104 is orbited about the axis of tubular member 48 into the position shown in FIG. 8, and an additional reach of wire 124 is between the points 104, 102 behind the reach 122 and the lead reach 121. As shown in FIGS. 2 and 3, the lead reach 121, in part, is wrapped around the outer circumference of the I tube 48 so as to draw the reach 122 from the pin 104 and around the pin 102. Eventually the reach of wire 122 is bent tubular member 48 through an increasing angle.

As shown in FIG. 4, the wire and tube are rotated 180 from the position shown in FIG. 3 into a second turn, the lead reach 121 and the part of the reach 122 that is connected thereto form a first loop 126 on the outer circumference of the tubular member 48. The first loop 126 is characterized by having bent ends 128, 130 thereon bent around a part of the outer circumference of the member 48 'to be located in good heat transfer contact with an arcuate segment of the outer surface of the tubular member 48. The ends 128, 130 extend from their bent contact with the member 48 to be joined to an apex portion 132 located radially outwardly of the outer circumference of the tube 48 to form an airflow passageway 134 between the loop 126 and the tubular member 48. At the stage of the winding shown in FIG. 4, the reach 124 is located with respect to "the tubular member 48 as was the reach 122 in the stage shown in FIG. 3, and another reach of wire 136 is drawn by the point 102 about the point 104 rearwardly of the reach 124.

Following the first loop 126, as shown in FIG. 4, rotated 360 in its second turn, the wire loop 126 is positioned, as illustrated in FIG. 5, and the reach of wire 124 is bent around the outer periphery of the tubular member 48. At this point the portion of the reach of wire 124 connected to the reach of wire 122 forms a second loop 138 having end portions 140, 142 bent into good heat transfer contact with the outer circumference of the tubular member 48 and closed on a portion of the circumference of the tubular member located behind that portion contacted by the ends 128, 130 of the loop 126. The loop 138 has an apex portion 143 like that of loop-126.

The loop 138 is angularly offset from the loop 126 through an angle of approximately 214 in the illustrated embodiment of the invention.

At the stage of winding shown in FIG. 5, the reach of wire 136 is positioned as shown, and another reach of wire 144 is located between points 102, 104 behind the reach 136.

Upon a 180 portion of turn number three, as shown in FIG. 6, the loops 126 and 138 are positioned as shown and an additional loop 146 is formed by parts of the reaches 124 and 136 as were loops 126 and 138 as previously discussed. The loop 146, like the previous loops, has end portions 148, 150 that are bent about the outer circumference ofthe tubular member 48, and it, additionally, includes an apex 152 like those in the previously formed loops. At this stage of the winding, the reach 144 is positioned as illustrated and a still further reach 154 is located across points 102, 104 rearwardly of the reach 144. The added loop 146 is angularly offset from the last formed loop 138 through an angle ofZ 14 as shown in FIG. 6.

Further rotation of the wire and tube with respect to one another produces a continuous formation of angularly offset loops on the tubular member 48 with succeeding loops having the same angular displacement-with respect to one another and being located at axially spaced points on the length of the tubular member 48.

In FIGS. 7 and 8, a number of the finished loops on the tubular member 48 are illustrated including the sequentially formed loops 126, I38, 146 and succeeding loops, 156, 158. These loops, in one form of the present invention, constitute a five-point loop system which is repeated upon continually rotating the wire and tube at loops 160, 162, 164, 166 and 168. It will be noted that by preselecting a particular angle between the succeeding loops the formed loops in each set of five points are angularly offset from one another. Thus, in FIG. 7 the initial loops that are located on the top of the tubular member eventually curve downwardly about the outer circumference of the tubular member 48 so that the space 170 bounded by the top loops 126, 160 and side loops 156, 166 moves in a counterclockwise curvilinear fashion about the outer periphery of the tubular member and likewise the space 172 between the top loops 126, 160 and the opposite side loops 146, 164 moves upwardly in a counterclockwise direction about the outer periphery of the tube. Spaces 174, 176 and 178 between other of the loops move in a similar curvilinear fashion about the outer circumference of the tubular member 48 along the length thereof.

By virtue ofthis arrangement, when the wire fin and tubular member are located in certain environments, for example, as an evaporator section in a frostproof refrigerator, when cold moist air is passed over certain of the loops, as for example the loops 126, 160, so as to deposit frost thereon to close a gap 180 therebe'tween, and assuming that airflow is passing from the space I70 to the space 172, as seen in FIG. 7, when the flow passageways 180 are blocked, the space 170 will provide relief for the airflow about the wire fin tube section so that cold air will be continually circulated in the system.

While the embodiment of the present invention as herein disclosed institutes a preferred form, it is to be understood that other forms might be adopted.

I claim:

I. A wire and tube heat exchanger assembly comprising, an elongated tubular member having an outer periphery and a fluid flow passageway, a continuously formed wire fin on the outer periphery of said member for transferring heat from a first fluid in said passageway to a second fluid on the outer periphery of said member, said wire fin including a plurality of loops each being offset one from the other through a predetermined angular displacement about said tube, each of said loops having first and second bent ends crossed at a radially inwardly located portion thereof, each of said loops including an apex portion located radially outwardly of said tube, each of said first and second bent ends of said loops being located on either side of said tube and engaging the outer periphery of said member through more than at spaced arcuate seg-.

ments of said tube for heat transfer through more than a point contact, said first and second bent ends of each of said loops being joined radially outwardly of said tube to said apex portion of said loop to define a flow path between said tube and said apex portion for the second fluid.

my 7 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Jul 13, 1971 Patent No. 3 ,592 262 Dated Inventor (5) Byron L. Brucken It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 11, "60" should be 68 Signed and sealed this 25th day of January 1972.

(SEAL) fittest:

EDWARD M.FLETGHER, JR. ROBERT GOTTSCHALK Attesting Office! Commissioner of Patents 

1. A wire and tube heat exchanger assembly comprising, an elongated tubular member having an outer periphery and a fluid flow passageway, a continuously formed wire fin on the outer periphery of said member for transferring heat from a first fluid in said passageway to a second fluid on the outer periphery of said member, said wire fin including a plurality of loops each being offset one from the other through a predetermined angular displacement about said tube, each of said loops having first and second bent ends crossed at a radially inwardly located portion thereof, each of said loops including an apex portion located radially outwardly of said tube, each of said first and second bent ends of said loops being located on either side of said tube and engaging the outer periphery of said member through more than 90* at spaced arcuate segments of said tube for heat transfer through more than a point contact, said first and second bent ends of each of said loops being joined radially outwardly of said tube to said apex portion of said loop to define a flow path between said tube and said apex portion for the second fluid. 